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/*
* Copyright (C) 2013 Michael Brown <mbrown@fensystems.co.uk>.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
FILE_LICENCE ( GPL2_OR_LATER );
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <ipxe/retry.h>
#include <ipxe/timer.h>
#include <ipxe/ipstat.h>
#include <ipxe/fragment.h>
/** @file
*
* Fragment reassembly
*
*/
/**
* Expire fragment reassembly buffer
*
* @v timer Retry timer
* @v fail Failure indicator
*/
static void fragment_expired ( struct retry_timer *timer, int fail __unused ) {
struct fragment *fragment =
container_of ( timer, struct fragment, timer );
DBGC ( fragment, "FRAG %p expired\n", fragment );
free_iob ( fragment->iobuf );
list_del ( &fragment->list );
fragment->fragments->stats->reasm_fails++;
free ( fragment );
}
/**
* Find fragment reassembly buffer
*
* @v fragments Fragment reassembler
* @v iobuf I/O buffer
* @v hdrlen Length of non-fragmentable potion of I/O buffer
* @ret fragment Fragment reassembly buffer, or NULL if not found
*/
static struct fragment * fragment_find ( struct fragment_reassembler *fragments,
struct io_buffer *iobuf,
size_t hdrlen ) {
struct fragment *fragment;
list_for_each_entry ( fragment, &fragments->list, list ) {
if ( fragments->is_fragment ( fragment, iobuf, hdrlen ) )
return fragment;
}
return NULL;
}
/**
* Reassemble packet
*
* @v fragments Fragment reassembler
* @v iobuf I/O buffer
* @v hdrlen Length of non-fragmentable potion of I/O buffer
* @ret iobuf Reassembled packet, or NULL
*
* This function takes ownership of the I/O buffer. Note that the
* length of the non-fragmentable portion may be modified.
*/
struct io_buffer * fragment_reassemble ( struct fragment_reassembler *fragments,
struct io_buffer *iobuf,
size_t *hdrlen ) {
struct fragment *fragment;
struct io_buffer *new_iobuf;
size_t new_len;
size_t offset;
size_t expected_offset;
int more_frags;
/* Update statistics */
fragments->stats->reasm_reqds++;
/* Find matching fragment reassembly buffer, if any */
fragment = fragment_find ( fragments, iobuf, *hdrlen );
/* Drop out-of-order fragments */
offset = fragments->fragment_offset ( iobuf, *hdrlen );
expected_offset = ( fragment ? ( iob_len ( fragment->iobuf ) -
fragment->hdrlen ) : 0 );
if ( offset != expected_offset ) {
DBGC ( fragment, "FRAG %p dropping out-of-sequence fragment "
"[%zd,%zd), expected [%zd,...)\n", fragment, offset,
( offset + iob_len ( iobuf ) - *hdrlen ),
expected_offset );
goto drop;
}
/* Create or extend fragment reassembly buffer as applicable */
if ( ! fragment ) {
/* Create new fragment reassembly buffer */
fragment = zalloc ( sizeof ( *fragment ) );
if ( ! fragment )
goto drop;
list_add ( &fragment->list, &fragments->list );
fragment->iobuf = iobuf;
fragment->hdrlen = *hdrlen;
timer_init ( &fragment->timer, fragment_expired, NULL );
fragment->fragments = fragments;
DBGC ( fragment, "FRAG %p [0,%zd)\n", fragment,
( iob_len ( iobuf ) - *hdrlen ) );
} else {
/* Check if this is the final fragment */
more_frags = fragments->more_fragments ( iobuf, *hdrlen );
DBGC ( fragment, "FRAG %p [%zd,%zd)%s\n", fragment,
offset, ( offset + iob_len ( iobuf ) - *hdrlen ),
( more_frags ? "" : " complete" ) );
/* Extend fragment reassembly buffer. Preserve I/O
* buffer headroom to allow for code which modifies
* and resends the buffer (e.g. ICMP echo responses).
*/
iob_pull ( iobuf, *hdrlen );
new_len = ( iob_headroom ( fragment->iobuf ) +
iob_len ( fragment->iobuf ) + iob_len ( iobuf ) );
new_iobuf = alloc_iob ( new_len );
if ( ! new_iobuf ) {
DBGC ( fragment, "FRAG %p could not extend reassembly "
"buffer to %zd bytes\n", fragment, new_len );
goto drop;
}
iob_reserve ( new_iobuf, iob_headroom ( fragment->iobuf ) );
memcpy ( iob_put ( new_iobuf, iob_len ( fragment->iobuf ) ),
fragment->iobuf->data, iob_len ( fragment->iobuf ) );
memcpy ( iob_put ( new_iobuf, iob_len ( iobuf ) ),
iobuf->data, iob_len ( iobuf ) );
free_iob ( fragment->iobuf );
fragment->iobuf = new_iobuf;
free_iob ( iobuf );
/* Stop fragment reassembly timer */
stop_timer ( &fragment->timer );
/* If this is the final fragment, return it */
if ( ! more_frags ) {
iobuf = fragment->iobuf;
*hdrlen = fragment->hdrlen;
list_del ( &fragment->list );
free ( fragment );
fragments->stats->reasm_oks++;
return iobuf;
}
}
/* (Re)start fragment reassembly timer */
start_timer_fixed ( &fragment->timer, FRAGMENT_TIMEOUT );
return NULL;
drop:
fragments->stats->reasm_fails++;
free_iob ( iobuf );
return NULL;
}
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